1. Field
The present specification generally relates to methods for cutting an article from a glass substrate and, more specifically, to methods for laser cutting an article from a chemically strengthened glass substrate.
2. Technical Background
Thin chemically strengthened glass substrates have found wide-spread application in consumer electronics because of their excellent strength and damage resistance. For example, such glass substrates may be used as cover sheets for LCD and LED displays incorporated in mobile telephones, display devices such as televisions and computer monitors, and various other electronic devices. Such glass substrates used in consumer electronics devices may be formed by sectioning or separating a large glass substrate into a plurality of smaller glass substrates using various cutting techniques.
Chemically strengthened glass has surfaces which are under compression and an interior region which is under tension. Elastic energy, proportional to the square of the central tension, is stored in this central tensile region. As an example, surface compressions of greater than 750 MPa and compressive layer depths greater than 40 μm may be present in chemically strengthened glass.
High surface compression and deep surface compressive layers are beneficial for scratch and damage resistance, but make it difficult to mechanically scribe the glass as in traditional scribe-and-bend processes. Furthermore, if the stored elastic energy is sufficiently high, the glass will break in an explosive manner when the surface compression layer is penetrated. In other instances, the release of the elastic energy may cause the break to deviate from a desired cut line, thereby damaging the glass substrate.
Additionally, the process of cutting or separating glass via laser ablation is relatively slow because the glass removal rate is very low. Another issue with this technique is the poor edge finish quality, which is almost always left with weakening defects. This type of process tends to generate a great deal of debris. The laser ablation process also requires an additional mechanical breaking step following the laser scribing or defect creation.
Scribe-and-bend and laser ablation processes may perform quite well in separation of non chemically strengthened glass in straight lines, but are limited in operations that involve cutting more complex shapes. Furthermore, the challenge in cutting chemically strengthened glass can be much larger than for cutting other ordinary sheets of glass.
Accordingly, a need exists for alternative methods for cutting chemically strengthened glass substrates.